Human spaceflight is one of the great achievements of the modern age. Not content to master flight in the atmosphere, inventors, engineers, scientists, and visionaries pressed ahead to explore space and developed the technology for human spaceflight. With varying degrees of political leadership and public support, the United States, Soviet Union/Russia, and other nations have made human spaceflight a priority.

Since the first venture into space by Soviet cosmonaut Yuri Gagarin in 1961, more than 500 men and women have flown in space, some staying months at a time. People have circled the Earth in small capsules and huge space shuttles. They have floated in open space, delivered satellites, conducted laboratory experiments, repaired space telescopes, and built a space station. Twenty-four men have flown to the Moon and back (three went twice), and twelve explored its landscape.